Predistortion-based amplifier, transmitter and envelope detector

Abstract

A predistortion-based amplifier which compensates for distortions generated by the amplifier when a modulated wave signal is amplified thereby in accordance with a predistortion scheme, based on envelope information of the modulated wave information. An envelope information detector for detecting information related to the envelope of the modulated signal to be amplified comprises, between an input terminal A 1 and an output terminal A 2 , matching circuits 11, 14 , diode circuits 12, 15, 16 for rectifying the modulated wave signal, a stub circuit 13 for removing a carrier component of the signal output from the diode circuits, and a signal converter circuit 17 for converting an envelope signal output from the stub circuit from a current signal to a voltage signal.

What is claimed is:  
     
       1. A predistortion-based amplifier comprising: 
       distributing means for distributing a modulated wave signal to be amplified;  
       distortion generating means for generating at least one of amplitude distortion and phase distortion in one of distributed signals;  
       an amplifier for amplifying the one distributed signal including the distortion generated by said distortion generating means;  
       an envelope information detector for detecting information related to an envelope of the other distributed signal; and  
       distortion control means for controlling the distortion generated by said distortion generating means so as to compensate for a distortion generated by said amplifier based on the result of a detection by said envelope information detector,  
       wherein said envelope information detector is constituted by using a stub circuit for removing a carrier component of the modulated wave signal.  
     
     
       2. The predistortion-based amplifier according to  claim 1 , wherein: 
       said stub circuit of said envelope information detector includes a plurality of stub portions.  
     
     
       3. The predistortion-based amplifier according to  claim 1 , wherein: 
       said envelope information detector includes a matching capacitor, a diode for rectifying a signal, an L-shaped microstrip line having a stub portion, a matching coil, an RF choke coil for biasing said diode, a voltage source for biasing said diode, and a resistor, wherein an input terminal for receiving the modulated wave signal is connected to one end of said matching capacitor, the other end of which is connected to an anode of said diode, a cathode of said diode is connected to one end of one side of said L-shaped microstrip line, the other end of the one side of said L-shaped microstrip line is connected to an output terminal, a point between said input terminal and said matching capacitor is grounded through said matching coil, said biasing voltage source is connected between said matching capacitor and said diode through said RF choke coil, and a point between said microstrip line and said output terminal is grounded through said resistor.  
     
     
       4. The predistortion-based amplifier according to  claim 2 , wherein: 
       said envelope information detector includes a matching capacitor, a diode for rectifying a signal, an inverted C-shaped microstrip line having two stub portions, a matching coil, an RF choke coil for biasing said diode, a voltage source for biasing said diode, and a resistor, wherein an input terminal for receiving the modulated wave signal is connected to one end of said matching capacitor, the other end of which is connected to an anode of said diode, a cathode of said diode is connected to one end of one side positioned between the remaining two sides of said inverted C-shaped microstrip line, the other end of the one side of said inverted C-shaped microstrip line is connected to an output terminal, a point between said input terminal and said matching capacitor is grounded through said matching coil, said biasing voltage source is connected between said matching capacitor and said diode through said RF choke coil, and a point between said microstrip line and said output terminal is grounded through said resistor.  
     
     
       5. A transmitter comprising a predistortion-based amplifier for amplifying a modulated wave signal to be transmitted, said transmitter transmitting the amplified modulated wave signal, said predistortion-based amplifier comprising: 
       distributing means for distributing a modulated wave signal to be amplified;  
       distortion generating means for generating at least one of amplitude distortion and phase distortion in one of distributed signals;  
       an amplifier for amplifying the one distributed signal including the distortion generated by said distortion generating means;  
       an envelope information detector for detecting information related to an envelope of the other distributed signal; and  
       distortion control means for controlling the distortion generated by said distortion generating means so as to compensate for a distortion generated by said amplifier based on the result of a detection by said envelope information detector,  
       wherein said envelope information detector provided on the predistortion-based amplifier is constituted by using a stub circuit for removing a carrier component of the modulated wave signal.  
     
     
       6. The transmitter according to  claim 5 , wherein: 
       said stub circuit of said envelope information detector forming part of said predistortion-based amplifier includes a plurality of stub portions.  
     
     
       7. The transmitter according to  claim 6 , wherein: 
       said transmitter is for use in a CDMA-based mobile radio communication system.  
     
     
       8. The transmitter according to  claim 5 , wherein: 
       said envelope detector forming part of said predistortion-based amplifier includes a matching capacitor, a diode for rectifying a signal, an L-shaped microstrip line having a stub portion, a matching coil, an RF choke coil for biasing said diode, a voltage source for biasing said diode, and a resistor, wherein an input terminal for receiving the modulated wave signal is connected to one end of said matching capacitor, the other end of which is connected to an anode of said diode, a cathode of said diode is connected to one end of one side of said L-shaped microstrip line, the other end of the one side of said L-shaped microstrip line is connected to an output terminal, a point between said input terminal and said matching capacitor is grounded through said matching coil, said biasing voltage source is connected between said matching capacitor and said diode through said RF choke coil, and a point between said microstrip line and said output terminal is grounded through said resistor.  
     
     
       9. The transmitter according to  claim 6 , wherein: 
       said envelope information detector forming part of said predistortion-based amplifier includes a matching capacitor, a diode for rectifying a signal, an inverted C-shaped microstrip line having two stub portions, a matching coil, an RF choke coil for biasing said diode, a voltage source for biasing said diode, and a resistor, wherein an input terminal for receiving the modulated wave signal is connected to one end of said matching capacitor, the other end of which is connected to an anode of said diode, a cathode of said diode is connected to one end of one side positioned between the remaining two sides of said inverted C-shaped microstrip line, the other end of the one side of said inverted C-shaped microstrip line is connected to an output terminal, a point between said input terminal and said matching capacitor is grounded through said matching coil, said biasing voltage source is connected between said matching capacitor and said diode through said RF choke coil, and a point between said microstrip line and said output terminal is grounded through said resistor.  
     
     
       10. The transmitter according to  claim 7 , wherein: 
       said envelope information detector forming part of said predistortion-based amplifier includes a matching capacitor, a diode for rectifying a signal, an inverted C-shaped microstrip line having two stub portions, a matching coil, an RF choke coil for biasing said diode, a voltage source for biasing said diode, and a resistor, wherein an input terminal for receiving the modulated wave signal is connected to one end of said matching capacitor, the other end of which is connected to an anode of said diode, a cathode of said diode is connected to one end of one side positioned between the remaining two sides of said inverted C-shaped microstrip line, the other end of the one side of said inverted C-shaped microstrip line is connected to an output terminal, a point between said input terminal and said matching capacitor is grounded through said matching coil, said biasing voltage source is connected between said matching capacitor and said diode through said RF choke coil, and a point between said microstrip line and said output terminal is grounded through said resistor.